Assessment of bone metastases in patients (pts) with urothelial carcinoma using 18 F-sodium fluoride PET/CT ( 18 F-NaF) versus 18 F-fluorodeoxyglucose PET/CT ( 18 F-FDG)

• Published in: Journal of clinical oncology Vol. 32; no. 4_suppl; p. 329
• Main Authors: Weinberg, Benjamin Adam, Lindenberg, Maria Liza, Kurdziel, Karen A., Steinberg, Seth M., Liewehr, David J., Khadar, Kattie, McKinney, Yolanda, Choyke, Peter L., Apolo, Andrea Borghese
• Format: Journal Article
• Language: English
• Published: 01.02.2014
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/jco.2014.32.4_suppl.329

Abstract only 329 Background: 18 F-NaF has shown improved sensitivity for bone imaging when compared to conventional planar imaging or SPECT/CT using 99m Tc-MDP. We compared the number of bone lesions detected on 18 F-NaF versus 18 F-FDG in urothelial cancer pts with known bone metastases undergoing treatment. Methods: Pts enrolled in a prospective single-arm phase II study of cabozantinib underwent 18 F-NaF and 18 F-FDG scans at baseline and at 8 weeks of therapy. In a lesion-based analysis independently confirmed by a nuclear medicine physician, abnormal foci of radiotracer uptake were categorized by location (skull, spine, pelvis, thorax, or long bones) and by disease state (benign, malignant, or indeterminate). A patient-based analysis was performed to determine if findings indicated disease progression, stable disease, or improvement of disease, based on the number of lesions and standardized uptake values (SUVs). Results: 294 total bone lesions were identified at baseline in 10 pts (8 male and 2 female, ages 44-73). 18 F-NaF identified more lesions than 18 F-FDG at baseline, 294 vs. 119. In a paired analysis, the median difference was 11.5 more lesions detected per patient on 18 F-NaF vs. 18 F-FDG (by Wilcoxon signed-rank test, p = 0.023). More total thoracic bone lesions at baseline, 100 vs. 23, were also detected on 18 F-NaF vs. 18 F-FDG, median 6.5 vs. 1.0 with a median difference of 6 more lesions per patient on 18 F-NaF (p = 0.016). 18 F-NaF also detected more skull lesions at baseline, 19 vs. 1, which was clinically but not statistically significant (p = 0.250). There was general concordance in the patient-based analysis; only 1 18 F-NaF scan demonstrated progressive disease while its corresponding 18 F-FDG scan showed stable disease. Conclusions: 18 F-NaF identified more lesions than 18 F-FDG at baseline, making it a good staging exam. However, there was agreement between 18 F-NaF and 18 F-FDG in terms of tumor response in almost all the follow-up scans. Therefore, although a greater number of bone lesions are seen in 18 F-NaF compared with 18 F-FDG, the clinical significance in assessing treatment response remains to be determined. Clinical trial information: NCT01688999.